Project Summary Signi?cance: A consumer-grade blood alcohol sensor has the potential to improve awareness of physiology of alcohol metabolism and reduce the incidence of alcohol related fatalities by helping individuals make safer, more educated decisions regarding alcohol consumption. Existing technologies such as personal breathalyzers require users to breathe into them, and thereby rely on impaired individuals to remember to perform a measurement to gather their blood-alcohol concentration readings. Existing alcohol monitoring technology such as WrisTAS and ankle-bracelets such as SCRAM have been inadequate for consumers due to their bulkiness, high cost, and fouling. Our hypothesis: Reliable blood alcohol concentration data for consumer applications can be achieved by means of disposable liquid-phase enzymatic sensor cartridges that measures transdermal alcohol concentration. Preliminary Data: In this proposal, ethanol detection through the skin is demonstrated with a cartridge-based disposable ethanol sensor and associated electronics that transmit data to a smartphone, with a response-time of two hours, and a cartridge shelf-life of one week at room temperature. Speci?c Aims: This project entails improving the response-time of the existing sensor to timescales less than one hour, increasing the shelf-life of the disposable cartridges to greater than six months, and verifying temperature stability of the sensor and integrated electronics in the range of 5 ? to 40 ?.